Communication is a social activity requiring the coordinated efforts of two or more individuals. Mere talk to produce sentences, no matter how well formed or elegant the outcome, does not by itself constitute communication. Only when a move has elicited a response can we say communication is taking place. To participate in such verbal exchanges, that is, to create and sustain conversational involvement, we require knowledge and abilities which go considerably beyond the grammatical competence we need to decode short isolated messages. We do not and cannot automatically respond to everything we hear. In the course of our daily activities we are exposed to a multitude of signals, many more than we could possibly have time to react to. Before even deciding to take part in an interaction, we need to be able to infer, if only in the most general terms, what the interaction is about and what is expected of us. For example, we must be able to agree on whether we are just chatting to pass the time, exchanging anecdotes or experiences, or whether the intent is to explore the details of particular issues. Once involved in a conversation, both speaker and hearer must actively respond to what transpires by signalling involvement, either directly through words or indirectly through gestures or similar nonverbal signals. The response, moreover, should relate to what we think the speaker intends, rather than to the literal meanings of the words used.